At the weekend I went on an urban forage in Exeter with Robin Harford. There were a couple of really interesting things I learned. The first thing that Robin teaches is that, in order to get to know and correctly identify edible wild plants, you really need to be present in the moment. It's no good being elsewhere, trying to remember what you've read in a book, thinking ahead to what you have to do next. You have to be there, seeing what's in front of you, smelling it, tasting it, paying attention. To do otherwise is to risk going with the ideas of the people around you and over-riding your instincts, which can be literally fatal! Having spent a few minutes doing this, the state stayed with me for the rest of the day and dramatically improved my photography - lesson learned there!

The second striking thing I learned was how many of the weeds that I routinely pull from my garden and compost are good eating. I knew about some of them, but others, like herb bennet, were new to me. I had tasted some, but the missing piece of knowledge was that you have to eat them at exactly the right time. A few weeks too late, and the bitterness is likely to have taken over and made the plant unpalateable. Plant populations also vary dramatically in how tasty they are, so just because I've tasted chickweed once and didn't much like it, doesn't mean that it's never worth tasting again - noted!

Weeds are weeds for a reason - like all pests, they don't share - so they have to be controlled, for all the hippy talk about trusting nature. Plus they make great bulk for the compost, so I'm not giving up weeding soon, but since I am creating a more easy-going, edible garden with all sorts of edible plants alongside the conventional veg, it makes sense to leave some of them to grow for harvest. Wild plants tend to be substantially more nutrient dense that cultivated plants, and have many medicinal uses, knowledge of which has been all but lost from our culture. Given that our primate relatives know and eat hundreds of different species of plants, it seems likely that we need to eat a much wider range of plant food than the standard 20 or so species in the Western diet to stay healthy. My dog picks out particular species of plants in the hedge to eat, dog's mercury especially, for reasons known only to her instincts, and all grazing animals will pick out particular plants to eat at particular times. Humans still have these instincts, even if they are deeply buried, and it can only be a good thing to re-awaken them. Plus, the plants are free, grow themselves and are tasty - what's not to love?

The part of Dorset where I live is quite unspoiled in terms of biodiversity, probably because the land is so poor for agriculture, and so there are lots of wildflowers, and many different plants seed themselves on my plot. Among them are several of the Umbellifer (carrot) family. Now I love the wild carrots and I'm quite familiar with cow parsley, but I'm wary of picking any of these plants because the family includes hemlock and hemlock water dropwort, which are deadly poisonous! I know that hemlock water dropwort grows along the river bank, and I suspected that one of the umbellifers I was routinely weeding out in the forest garden might be hemlock, and indeed, as Robin showed us, it is! On the plus side, I realised that I really do know how to identify cow parsley and it is a good edible, and now I know how to identify hemlock. Cow parsnip and the others remain to be learned!

Foragers can sometimes be a bit sniffy to growers, citing agriculture as a recent innovation, only 10,000 years old, but I fail to see why I have to be one or the other. Surely the boundaries between foraging and growing have always been blurry. The first garden must have come about when some forager got bored of walking three miles to pick their favourite plant and transplanted some to close to the back door. Similarly, when agriculture fails us, we resort to foraging, or when there is a seasonal bounty that we fancy, like blackberries.

I consciously aim to blur the boundaries between the two on my plot, with wild edible plants and fungi encouraged to grow and edible annuals encouraged to self-seed, alongside edible perennial vegetables and a conventional vegetable garden. The garden should merge into the surrounding wild vegetation rather than there being a clear boundary.

Edible plants, in all shapes and sizes, are where it's at, and with everything that I learn about them, I become more aware of how little I know.

Please don't take my word for it that these plants are edible, or that of any amateur - please consult an expert or several different guidebooks before eating! See eatweeds.co.uk for more information by Robin Harford.